Separation of 2-nitronaphthalene-4, 8-disulphonic acid from isomers



Patented Dec. 15, 1931 "UNI STATES PAT ITOFF E JOHN H. TINKER, OF SOUTH MILWAUKEE, Alli) hflillltill'oltl A. HANSEN, OF MILWAUKEE,

WISCONSIN, ASIGNORS, BY MESNE ASSIGNMENTS, TQ E. I. DU FONT NEMOURS 86' I COMPANY, A CO RPORATION or nnLAWAn-n' SEPARATION or V2-NITBONAPHTHALENE-4,8-DISULPHONICYACID FROM xsomnns H9 Drawing.

naphthalene-4,8-disulphonic acid rom oer-I tain isomers generally formed therewith in the process of its formation.

2-nitro-naphthalene-4,8 disulphonic acid is generally prepared by sulfonating naphthalene at low temperatures under conditions 10 mainly'leading to 1-5 and 1-6 disulf-o-com pounds, and then nitrating the product to the mono-nitro derivative. In this process the product is invariably contaminated with various isomers arising both during the sulfonation step and during the nitration step-h Chief among these are the and the 2,4,7-compounds.

v in U; S.Patent No. 1,756,537 is "described 1,4, the 1,3,8

mers 'by converting the 2,4,8 acid into its magnesium salt and precipitating this salt in an acid medium', L We have now foundthatt-the saidprecipi- 5 tation and separation from isomers can be effected bythe use of compounds of'metals belonging in the zinc-group in the well-known system of qualitative analysis comprisingthe successive elimination of the (1) silver group, (2) arsenic-copper group, and (3) aluminum group by the successive treatment of the unknown'solution with (1) H01, (2) H S, and

(3)'NH,OH. (See Julius StieglitZ, Qualita- ;tive Chemical Analysis; publishedby Century, New York, 1914:; Volume'II, pages 100to 113.) This group is characterized by being soluble inNI'LOH, but insoluble in (NHQgS in alkaline solution, and consists -ofthe elements Ni", Co, Mn, and Zn (See Ibid, page 109, paragraph (6).)-

We have found. that if an acid-soluble compound of one of these elements (for instance an oxide, hydroxide, or salt) be added to the mixtureof isomeric nitro naphthalene-disulphonic acid, inacid solution the 2,4,8-ison1er will beprecipitated inthe form of its corresponding salt leaving the other isomeric compounds in solution.

to separate 2 nitro-naphthalene, 4,8-disul- -a method of isolating the 2,4,8-nitronaph thalene-disulphonic acid from its various isowith a small quantityhf the Therefore, an object'of thisinvention is Application filed November 3, 1930. Serial No. 493,226, 1

phonic acid from its isomers by means of compounds of'metals belonging" to the zinc group of the said qualitative analysis system. A further important object of our inven-Q tion is the preparation of oertain salts of2- nitro-naphthalene, 4:,8-disulph0ni'c acid.

Other and further objects of this invention will be apparent from the disclosures in the following description, which sets forth the preferred form of our invention.

As the proportion of the'2,4,8-isomerin the reaction mass when produced by the method above'describ'ed is generally known fromprevious experience with thismethod, the requisite quantity of metallic compound 'tobe added to convert the 2,4,8-i'somer into its salt, can be readily estimated, However, this estimate need not be precise, since a slight excess of metallic ion "will not affect the separatiombut Will merely constitute a waste of' the metallic compound. fOn the other hand, a deficiency of themetalliccompoundwill leave some of the 2,4,8-isomer in solu tion. The best procedure is to add the metallic compound in small quantities until a sample of the mother liquor rseparately tested precipitant shows no further precipitation; l a, a

Our preferred method is to dilute the acid nitration mass to a concentration of about 10% sulfuric acid, and then add the precipi tating metal in the form of an oxide,hydrox5 ide, or a saltthereof. It is permissible, how-V ever, also'to add the precipitant first and then dilute. i

It will be understood; of course that instead of a singlemetal of the group above mentioned, a mixture of two'or more of these may be used, Similarly, instead of a singleicom pound of a given metala mixture of-two or more may be used; for instance, a mixture of various oxides, or of anfoiiide and. a by: droxide. V ,7

In'our process, we mayI start with the iso 1 mers in the free-acid form, or wemay useany acidmediumLf I We preferto" effect the addition of the metallic compound at at temperature of about suitable salt thereof which is soluble an 40 C., and then cool down the mixture to tures. The naphthalene-disulphonic acid soperatures, the -ous salts may be used Without detrimental results.

To further illustrate our invention, the following specific examples are submitted, but it should be understood that our invention. is not limited thereto.

li'zrample l The finished nitration mass made by sulfonating 10 parts of naphthalene with 52 parts of 24% oleum at 10 to C., dilutingwith 5 parts water then nitra'ting with 19.7 parts of nitric-sulfuric acid containing 25% nitric acid, sulfuric acid and 15% water, is poured into a sufficient amount of water to give a solution of 180 parts by volume and a temperature of 50 C. 2.3 parts of zinc oxide are then added and the mass cooled to 10 C. After stirringfor 3 to 4 hours the acid zinc salt of 2-nitro-4,8-naphthalenedisulphonic acid is filteredoff. The. isomeric nitro-acids in the mother liquor may be reduced to give a mixture ofthe amino-disulphonic acids, whiclrmay then be separated by well-known methods.

. Ewample 2 Cl,'is dissolvedina sufiicient amount of water.

to give a 10% sulfuric-acid solution at'30 CI l'O'pa-rts of'nickel sulfate crystals with G'mols of Water are added and'the-mass cooled to 15- C. After stirring for several hours the 2-nitro-naphthalene-4 ,S-disulphonic acid crystallizes out as a nickel salt and is filtered off. The isomeric nitro acids in the mother liquor may then be neutralized with lime and then reduced to the corresponding aminonaphthalene disulfoacids.

Emample 3v A solution of naphthalene disulphonic' acids is producedby disulfona't'io'n of 10 parts of naphthalene with oleum at 'low temperalution is then mono-nitrated with 'a sulfuric nitric acid mixture. The resulting nitro-' naphthalene disulphonic acid solution is freed of excess acid by diluting with water,

I precipitating the excess H3804 with lime,

; is-next made acid'to Congo red solution with 5 parts of sulfuric acid, 23 parts of cobaltic chloride are then added. After stirring several hours, the 2-nitronaphthalene-4,8- disulphonic acid crystallizes out as the cobalt salt and is filtered from theoth er isomers in the mother liquor; i

Ewample 4 A phonic acid. is prepared by disulfon-ating 10 parts of naphthalene with ole um atlow temperatures, and mono-nitrating the resulting naphthalene :disul'phonic acid..withb-a-sulfuricnitric acid mixture. The solution is then d-iluted'with water, and the excess-"sulfuric acid. is precipitated with lime. The calcium sulfate f oi'med'is filtered off and the soluble calcium injthe mother liquor is precipitated with'soda ash. The resulting calcium carbonate is next filtered off and the solution is now made aci'dwith 5"pa rts of hydrochloric acid toa pH value of about 1.2 to 4.6. 32 parts of manganic sulfate are then added. After standing several" hours, the 2-nitr0- naphthalene-4,8-disulphonic acid separates as the manganese salt 'aridis filtered off. The

isomeric nitro acids int'he mother liquor may be treated as in Example 1.

This-luvention involves a valuable commercial process for the separation of 2-nitronaphthalene4,8 disulphonic acid from its isomers as well as'tlie preparation of certain new metal salts of 2-nitro naphthalene-4c,8-

disulphonic acid, which have valuable uses in thea'rts. I

' In the claims below it shouldbe understood thatby the termnaturally occurring; isomers of'2 nitro-naphthztleneAfi-disulphonic acid we mean to refer to those isomerswhi'ch generally form therewith in the process of preparing the same by low temperature disul.- fonation and subsequent mono-nitration of naphthalene. i i p il e areaware that numerous details of the invention may be varied through a wide range without departing from the spirityof. this invention, and we donot desire limitingthe patent granted other thanas necessitated thalene-4,8.-disulphonic acid from its natu ialliv occurring isomers, "which comprises treating a solution containing-amixture of the said acids with a metallic compound, of

the groupronsisting of zinc, manganese.

cobalt and nickel.

2; Theprocess of separating 2-nitronaphtha:lene-4,8-disulphonic acid from its natu rally occurring isomers, which comprises treating a solution containing a mixture of the said acids with a metallic compound of the group consisting of zinc, manganese, cobalt and'nickel', and filtering ofi the resulting presolution of nitronaphtha leneadisulcipitated salt of the 2-nitro-naphthalene-4,8- disulphonic acid. Y

3. The process of separating 2-nitro-naphthalene-4,8-disulphonic acid from the mass obtained by nitrationof naphthalene disulphonic acid, which comprises treating thev diluted mass with a compound of a metal selected from the group consisting of zinc, manganese, cobalt and nickel;

4. In the separation of 2-I1Ilt10-11fiphtl1tl- ,lene-4,8-disulphonic acid from isomeric nitronaphthalene disulphonic acids normally associated therewith, the process which comprises formin a salt of 2-nitro-naphthalene- 4:,8-disulphon1c acid with a metal of V the group consisting of zinc, manganese, cobalt and nickel and allowing said salt to crystallize from a solution having an acid reaction.

5. The process of separating Z-nitro-naphthalene-4,8-disulphonic acid from the mass obtained by nitration of naphthalenedisulphonic acid, which comprises treating the subscribed our names at Carrollville, Milwaukee County, Wisconsin.

JOHN M. TINKER. VERNON A. HANSEN.

diluted mass with an acid soluble metal comv pound, the metal of which is a member of the group consisting of zinc, manganese,

cobalt and nickel, and filtering. off the resulting precipitated salt of the 2-nitro-naph-. thalene-4,8-disulphonic acid.

6. The process of separating Q-nitro-naphthalene-4,8-disulphonic acid from isomeric nitro-naphthalene-disulphonic acids formed therewith b nitration of naphthalenedisulphonic aci s, which comprises reacting a solution of the. nitration mass with zinc oxide and filtering off the resulting precipitated zinc salt of 2-nitro-4,8-naphthalene disulphonic acid.

7. As a new product of manufacture, a

metal compound of Q-nitro-naphthalene-4,8-

disulphonic acid, the metal being a member of the group consisting of zinc, manganese,

cobalt and nickel. i g V 8. As a new product of manufacture, a

metallic salt of Q-nit-ro-naphthalene-4,8-disulphonic acid, the metal'being a member of the group consisting of zinc, manganese, cobalt and nickel. I

9. As a new product of'manufacture, a zinc salt of 2-nitro-naphthalene-4,8-disulphonic acid.

10. The processof separating Q-nitro-naphthalene-4,8-disulphonic acid from isomeric nitro-naphthalene-disulphonic acids formed therewith by nitrationof naphthalene disulphonic acids, which comprises reacting a solution of the nitration mass with a nickelic salt and filtering ofli' the resulting precipitated nickel salt of 2-nitro-4,8-naphthalene-disulphonic acid.

11.- The process of separating 2-nitronaphthalene-4,8-disulphonic acid from isomeric nitro-naphthalene-disulphonic acids formed therewith by nitration of naphthalene disulphonic acids, which comprises reacting a solution of the nitration mass with 

